Loader bucket leveling control



May 1, 1962 J. 1.. FRENCH ETAL LOADER BUCKET LEVELING CONTROL 5 Sheets-Sheet 1 Filed Aug. 29, 1958 INVENTOR.

J.L.FRENCH C.G.TERMONT J.C.GUNN

L V v I 2 y 1962 J. L. FRENCH ETAL 3,032,215

LOADER BUCKET LEVELING CONTROL Filed Aug. 29, 1958 5 Sheets-Sheet 2 FIG 3 47 z -iq INVENTOR.

J.L. ENCHT O N 0.6. MON 3 N J.C.GUNN

May 1, 1962 .1. L. FRENCH ET AL LOADER BUCKET LEVELING CONTROL 3 Sheets-Sheet 3 Filed Aug. 29, 1958 2 9 O 8 8 m B 0 i l. 2 r I! I' mi a FIG. 6

FIG. 5

INVENTOR. J.L.FRENCH C.G.TERMONT J.C.GUNN

nited tats 3,032,215 LOADER BUCKET LEVELING CQNTROL John L. French, Charles G. Termont, and John C. Gunn, Moline, Ill., assignors to Deere & Company, Molina, 111., a corporation of Delaware Filed Aug. 29, 1958, Ser. No. 757,962 6 Claims. (Cl. 21414tl) This invention relates to a material loader and more particularly to a tractor-mounted front-end loader of the type including a vertically swingable boom at the front end of which a material handling bucket is carried.

In a typical construction of this type, the tractor provides a support or base at which the aft end of the boom structure is mounted for vertical swinging, normally achieved by hydraulic means. The fore end of the boom structure carries a tilting bucket which, in the down or lowered position of the boom structure, engages material as the tractor is driven forwardly and which, when the boom is raised, carries the material to a height enabling dumping of the bucket so as to transfer the material to a vehicle or to some other location. In the distant past the connection between the bucket and the boom, whereby the bucket is releasably held between loading and dumping positions, consisted of mechanical linkage operated from a remote location, such as at the operators control station on the vehicle. In the more recent past, hydraulic cylinders have been used for achieving this re sult.

One particular problem involved in the design of a commercially acceptable loader is that the level or loading position of the bucket be substantially maintained irrespective of the vertical position of the boom, because without such means the bucket will tend to tilt rearwardly, spilling the contents thereof. Accordingly, it is conventional to provide some form of self-leveling means for the bucket. These have heretofore primarily consisted of mechanical linkages incorporated to some extent with the means for releasing the bucket for tilting, but for the most part these leave much to be desired in the way of operational and cost considerations. According to the present invention, an improved leveling and control system is provided, incorporating a hydraulic motor for controlling the position of the bucket as between loading and dumping and further incorporating servo means for controlling a valve or similar operator for actuating the bucket motor or equivalent power device in such manner that the valve or operator is responsive to raising of the boom to operate the bucket motor or device in such manner as to substantially maintain the level condition of the bucket irrespective of the position of the boom. It is a further object of this invention in the respect noted to provide improved servo means substantially entirely housed within a hollow boom structure. A further ob ject resides in the use of a hydraulic system in series with the hydraulic system used for raising and lowering the boom. A still further object entails the incorporation of means in the control valve system enabling operation of the control valve manually or independently of the servo system.

The foregoing and other important objects and desirable features inherent in and encompassed by the invention will become apparent as a preferred embodiment thereof is disclosed in detail in the ensuing description and accompanying sheets of drawings, the several figures of which are described below.

FIG. 1 is a schematic view, partly in section, of the overall control arrangement as applied to a vertically swingable boom and tiltable bucket.

FIG. 2 is an enlarged section of the bucket control valve.

FIG. 3 is an enlarged fragmentary perspective illustrating the boom structure in a raised position and showing the relationship of the valve and bucket control cylinders thereto.

FIG. 4 is a perspective on a reduced scale showing a typical tractor-mounted loader of the character considered here.

FIG. 5 is an enlarged section on the line 5-5 of FIG. 3.

FIG. 6 is an enlarged section on the line 6-6 of FIG. 1.

An overall picture of the general machine may be best obtained from FIG. 4, wherein the numeral 10 represents a conventional track-laying tractor having rigidly mounted thereon a pair of transversely spaced apart upright supports 12. These, taken together, may be considered as a basic support for mounting the loader itself, which here comprises a pair of parallel fore-and-aft extending booms or arms 14 having their rear ends pivotally connected to the supports 12 on transversely coaxial boom pivots 16. The forward ends of the booms carry a conventional loader bucket or scoop 18, and the connection between the bucket and the fore ends of the booms is established by a pair of vertical clevises 20 rigidly secured to the back wall of the bucket and affording a pair of transversely coaxial bucket pivots 22. In FIG. 1, the lead lines from the numerals 16 and 22 are applied respectively to the centers or axes of the pivots just described in order to distinguish from shaft and other structure to be presently described. On the basis of the description thus far it will be seen that the booms 14 are vertically swingable as a unit about the boom pivot 16, hereinafter referred to in the singular, and that the bucket 18 is tiltable fore-and-aft about the bucket pivot 22, likewise hereinafter referred to in the singular.

The machine is equipped with means for effecting raising and lowering of the booms 14, and this means prefer-' ably takes the form of a hydraulic motor 24 having a cylinder 26 connected at 28 to the support 12 and a piston 30 having its rod connected at 32 to an intermediate under portion of the boom 14, it being understood that the structure is duplicated at opposite sides of the machine. The position of the bucket 18 relative to the boom 14 is controlled by a pair of power devices, here bucket control motors 34, one of each boom 14, and each comprising a cylinder 36 and piston 38 having its rod pivotally connected at 40 to the bucket clevis 20. The point 40 is spaced from the boom-to-bucket pivot 22.. The anchored end of the cylinder 36 includes a transverse pivot 42 on a bracket 44 that is rigidly secured to the associated boom.

The tractor, as is conventional, includes a power-driven hydraulic pressure source, such as a pump P having its suction side connected to a reservoir R and having its pressure side connected by a line 46 to a boom control valve 48. In a typical situation, the reservoir is part of the tractor casing structure; although, this is a detail not important here. The valve 48 is of any conventional open-center type having a pair of motor outlets 50 and 52 which are connected respectively by motor lines 54 and 56 to the front and rear ends of the cylinder 26 of the boom control motor 24, so that fluid is selectively supplied to and exhausted from opposite sides of the piston 30. When the valve 48 is in a neutral condition, fluid is discharged from a discharge outlet 58 in the valve 48 and is transmitted through a discharge line 60 to and norrnally through a bucket control valve or operator 62 and thence to reservoir via a reservoir line 64. For the present, the details of the bucket control valve 62 may be ignored, and it may be observed that the boom control valve 48 can be changed, as by a hand lever 66, pivoted to the support as at 68, from a neutral condition as shown in FIG. 1, to either of two active positions, in which the pressure line 46 is connected, for example, to the motor outlet 52 for pressurizing the rear end of the motor 24, whereby to extend the motor for raising the boom Fluid returning from the opposite end of the motor 24 via the line 54 is connected by the valve from the motor outlet 50, which is now an inlet, to the discharge 58 and thence via the line 60 and valve 62 to the reservoir at 64. Rocking of the hand lever 66 in the opposite direction will condition the valve 48 for its other active position, in which the motor lines are reversed so that fluid returns to the reservoir from the rear end of the motor 24 via the line 56, outlet 52 (now an inlet), discharge outlet 58, discharge line 60, valve 62 and reservoir line 64. For present purposes, the boom control may be considered conventional, except for the series connection of the discharge outlet 58 and the valve 62, since the line or conduit 61) in this instance provides a pressure inlet 70 (FIG. 2) for the valve 62.

a The valve 62, in addition to the inlet 70, has a pair of motor outlets 72 and 74 and these are connected by motor lines 76 and '78 respectively to the rear end and front ends of the motor 34, so that fluid under pressure can be selectively supplied to or exhausted from the cylinder at opposite sides of the piston 38. When the bucket control valve 62 is in its neutral position, as shown in FIG. 1, the motor outlets 72 and 74 are cut oif from the pressure inlet 70 and the motor 34 is thus hydraulicallylocked. At the same time, the pressure inlet 70 is connected to an outlet 80 in the valve which is connected to reservoir by the previously described line 64 (FIG. 2). The valve 62, as will be presently described, is so designed and constructed that it has two active positions, one at either side of the neutral position. In one active position, the valve supplies fluid under pressure to the rear end of the bucket motor 34 so as to extend this motor for tilting the bucket forwardly and downwardly about the boom-to-bucket pivot 22. In the otheractive position of the valve 62, fluid under pressure is supplied by the line 7 8 to the forward end of the bucket motor for tilting the bucket rearwardly. The valve 62' is under control of a second hand lever 82, pivoted. to the support 12 as at 84 and associated with a rack or quadrant 86 for holding any one of several positions that the lever 82 may occupy.

The valve 62 comprises a pair of relatively movable parts, one of which is a housing 83 and the other of which is an axially shiftable valve spool 90. The housing 88 has formed therein the pressure inlet 70, the motor outlets 72 and 74 and the reservoir outlet 89 as well as other passages to be described. The valve spool has opposite end lands 92 and 9 3 between which end capes 96 and 98 and centering springs 16% and 162 operate to maintain the spool 90 in a central or neutral position in which intermediate lands 104 and 106 cut oh" the pressure inlet '70 from the motor outlets 72 and 74 and wherein grooves at opposite sides of a central land 108 enable communication between the branched pressure inlet 76 and the reservoir outlet 80. The boom control valve 48 may be of identical construction, which establishes the constant communication between the pressure line 46 and the discharge outlet 58; that is to say, in the neutral position of the valve 48, the pressure line 46 is connected across the valve to the discharge outlet 58 in the same manner that, in the valve 62, the pressure inlet is connected across that valve to the reservoir outlet 80; and, in either active position of the valve 48, the return from the non-pressurized end of the motor 24 is connected to the discharge outlet 58. In other Words, there is a constant supply of fluid under pressure from the valve 48 serving as the pressure inlet source for the boom control valve 62. Hence, the two valves are connected in series, and may be operated independently or simultaneously by the respective hand levers 66 and 82.

Considering operation of the valve 62 as constantly supplied with fluid at 70, it will be seen that in its neutral position, the fluid escapes through the branches of the inlet 70 and between the central land 108 and the two adjacent lands 104 and 166 for exhaust via to the reservoir at 64. When the valve parts 83 and are shifted relative to each other to one active position, one end of the motor 3 will be pressurized and the other will be exhausted. For example, let it be assumed that the relative movement incurs upward shifting of the housing 88 and downward shifting of the spool 90. In that case, the upper land 92 will retain its blocking relationship to the upper branch of the exhaust or reservoir outlet 80, and the next uppermost land 1114 will move past the upper branch of the inlet 70 so that this branch is connected to the motor outlet 72, thereby supplying fluid under pressure through the line 76 to the rear end of the bucket motor 34. At the same time, the lands 108 and 166 will isolate the other branch of the inlet 70 from both the motor outlet 74 and the reservoir outlet 86, but the lowermost land 94, in moving downwardly, will connect the motor outlet 74 to the reservoir outlet 80. Hence, fluid returning from the front end of the motor 34 via the line 78 will return to reservoir via 74-80-64. The opposite result will occur in the other active position of the valve 62; that is, when the valve parts are moved relatively so that the valve housing 88 moves downwardly and valve spool 96 moves upwardly. As already stated, the neutral condition of the valve is automatically achieved by the centering springs 1G0 and 102 upon the removal of extraneous forces.

As will be seen, if the bucket 18 is maintained rigid with the boom via the hydraulic lock on the bucket motor 34 and the boom 14 raised, the level of the bucket.

18 would change, inasmuch as the bucket would tilt rearwardly as the boom 14 moves upwardly. As will be further seen, if the valve 62 can be actuated to supply fluid to the rear end of the motor 34 as the-boom 14 is raised, the motor 34- would extend and would tilt the bucket forwardly, correcting its tendency to tilt rearwardly. Therefore, it becomes expedient to connect some means between the boom and the valve 62 for automatically operating the valve 62 to correctively return the bucket 18 to its level position irrespective of the vertical position of the boom 14. Such means is provided according to the present invention.

As best shown in FIG. 5, the boom pivot 16 between one oi the booms 14 and the associated support 12 is in the form of a shaft 116 coaxial or coincident withthe pivot 16 and enlarged at one end in the form of a head or plate 112 to which is rigidly aflixed an arm or arm means 114 eccentric to the pivot 16. The shaft and its associated portion 112 constitute a rockable member which is journaled in the proximate portions of the, boom 14 and support 12, as by bushings 116, and this rockable member is augmented by a sheave or equivalent member having an outer arcuate surface concentric about the axis 16, the member in this instance being shown as a grooved wheel or sheave 118 keyed to the shaft at 120. The arm 114 extends rearwardly and is pivotally connected at 122 to the valve part 90 comprising the spool of the bucket control valve 62.

The valve 62 is connected to the lever 82 which thus constitutes a manually movable device for acting on the valve means. In the present case, the lower end cap 98 of the valve housing or part 88 is rigidly connected to the upper part of a spring-loaded linkage 124 and this linkage is in turn connected to the lower part of the lever 82. Spring loading of the linkage, as by a spring 126, acts between upper and lower washers 128 and 131) to enable spring loading of the linkage either upwardly or downwardly. The spring 126 is heavier than the centering springs and 102 in the 'valve 62. For present purposes, and ignoring for the moment the function of the linkage as a spring-loaded device, it will be seen that the linkage establishes .a connection between the lever 82 and the valve part or housing 88 whereby the housing may be shifted relative to the spool 90, assuming the latter to be fixed by its connection to the arm 114 of the upper rockable member 110112.

The rockable member just referred to comprises part of servo means instrumental in leveling of the bucket 18 and acts to shift the valve 62 into and out of its neutral positions as the boom 14 raises. Another part of the servo means comprises a second rockable member or sheave 132, mounted coaxially with and keyed at 136 to one of the boom pivots 22 (FIG. 6). The pin 22 is headed at 138 and is rigidly connected to one side of the proximate clevis 20, as by cap screws 140. This is merely a representative connection, since other connections between the bucket and sheave 132 may be resorted to. The purpose of the connection is so that the sheave 132 turns about the bucket pivot 22 when the bucket turns about the same pivot. In order that motion of the bucket about the bucket pivot 22 may be transmitted to the upper end of the structure so as to act on the valve 62, a forcetransmitting connection is applied, here taking the form of a force-transmitting element or cable 142 wrapped partially about the grooved outer surface of the sheave 132 and having its terminal end secured to the sheave at 14-4. The other end of the cable 142 is trained about the upper sheave 118 and is returned forwardly to a free end 146 which is connected to one end of a tension spring 148, the opposite end of which is anchored to an under portion of the boom at 150. The cable 142 is thus tensioned by the spring 148 and is positively connected to and wrapped around the sheave 132 and frictionally engages the groove in the upper sheave 118. The boom is of hollow or tubular construction and has an upper closure 152 and a lower closure 154, whereby the servo means is substantially entirely enclosed within the boom. A guide roller 156 is provided at the upper end of the bottom closure 154 to guide the free end portion 146 of the cable to its connection to the spring 148.

In the operation of the servo means as controlling the corrective leveling of the bucket 18 as the boom 14 raises, it should be noted that the point of tangency between the cable 142 and the sheave 132 is obviously spaced from the bucket pivot axis 22, and this is true of the cable 142 as respects the sheave 118 at the boom pivot 16. Hence, the cable, being under tension by means of the spring 148, establishes, relative to the points of tangency and the centers or axes 22 and 16, a parallelogram. As the boom 14 is raised, the parallelogram changes, the points of tangency moving rearwardly so that the upper stretch of the cable 142 also moves rearwardly under tension of the spring 148. This rotates the upper sheave 118 in a clockwise direction as seen in FIG. 1, and the arm 114 applies a downward force to the valve spool 90. As already indicated, the load on the spring 126 in the spring-loaded linkage 124 is relatively strong and for present purposes the linkage may be considered solid. Therefore, it holds the valve housing 88 against downward shifting and consequently the two valve parts move relatively, the valve spool moving downwardly so that the upper intermediate land 104 establishes connection between the upper branch of the pressure inlet '76 and the motor line 76 to the rear end of the bucket motor 34. Since, when the boom 14 and bucket 18 move upwardly, the tendency of the bucket is to depart from a level position by inclining rearwardly, extension of the motor 34 will correctively position the bucket so that it returns toward its level position. As the bucket does so correctively return to its level position, it turns the sheave 132 counterclockwise, rearranging the parallelogram of which the stretch of the cable 142 forms the upper part and therefore rotates the upper sheave 118 in a counterclockwise direction, reshifting the valve spool 90 upwardly as distinguished from its previous downward shifting, thereby restoring the valve parts to their neutral 6 position and discontinuing the supply of fluid to the motor 34.

It should be understood, however, that the above action is repeated infinitely as the boom 14 elevates. On the same basis, then, if the boom 14 is raised to a certain position, including an intermediate position, the situation at that time will be one in which the bucket has been leveled by recurring action of the servo means on the valve means 62, and the bucket will be level irrespective of the position in which the boom 14 is stopped.

Reverse action occurs as the boom 14 is lowered and when the boom reaches the position of FIG. 1, the bucket 18 will again be level and ready for digging or scooping.

It has become conventional in recently designed loaders to provide means for forcibly tilting the bucket 18 rearwardly from its loading position, which is a feature instrumental in breaking loose relatively difiicult loads. That result can be achieved here by overriding the servo means by the hand lever 82. For example, the result just described is effected by applying fluid under pressure to the forward end of the bucket motor 34, and this is done by moving the hand lever 82 back so as to operate through the linkage 124 to pull down on the valve housing 88, the spool 90 being retained by its connection at 122 to the now fixed arm 114. This has the same effect of moving the valve spool 90 upwardly, and it will therefore be seen that movement of the spool as indicated causes the land 1116 to shift upwardly beyond the lower branch of the pressure inlet 70 and at the same time to retain connection with the motor outlet 74, whereby the motor line 78 to the front of the motor 34 is pressurized. Return fluid is carried by the line 76 through the valve 62 to the reservoir at 64. Because of the servo means and the action thereof in restoring the valve parts 88 and 90 to neutral, it is necessary that the servo means be overridden at any time in which the bucket is manually controlled, as in the instance just described. Otherwise, the servo means would tend to return the valve to neutral. Therefore, the spring 126 in the linkage 124 enables movement of the lever 82 through a range greater than that required to shift the valve parts 88 and 90 relatively. The same is true in achieving the dumping position of the bucket after the boom and bucket are raised. That is to say, the lever 82 can be moved forwardly through a considerable range, exerting an upward force on the valve housing 88 relative to the temporarily fixed spool 90, the linkage 124 collapsing to accommodate the difference in ranges of movement between the lever 82 and valve 62. Hence, in either case, even though the servo means does tend to center the valve parts, the continuing force supplied by the spring 126, which as previously stated acts in both directions, overrides or overcomes the servo means and keeps the valve in the selected active position to accomplish the manually directed selected operation of the bucket.

Reference was previously had to the connection of the valves 62 and 48 in series. By this means, the discharge 58 of the valve 48 always supplies fluid under pressure to the valve 62 for accomplishing the follow-up function necessary to attain corrective leveling of the bucket, irrespective of whether the valve 48 is neutrally or actively positioned. Likewise, the two levers 66 and 82 may be operated independently or simultaneously or in any sequence.

The control arrangement is simple and inexpensive and is relatively easily applied to existing constructions as well as being capable of being incorporated in new constructions. Features other than those categorically enumerated will readily occur to those versed in the art, as will many modifications and alterations in the preferred embodiment disclosed, all of which may be achieved without departure from the spirit and scope of the invention.

What is claimed is:

1. In a loader having a support mounting the aft end of a fore-and-aft boom on a transverse boom pivot, a bucket carried by the fore end of the boom on a transverse bucket pivot for fore-and-aft tilting to opposite sides of a generally level position and means for effecting raising and lowering of the boom, the improvement residing in means for correctively maintaining said level position of the bucket as the boom is raised and lowered, comprising: means including a reversible fluid motor conneoted between the boom and the bucket for tilting the latter selectively fore-and-aft about the bucket pivot; valve means including a pressure inlet and a pair of motor outlets connected respectively to opposite sides of the motor and a pair of relatively movable valve parts changeable from a neutral position cutting olf the motor outlets from the pressure inlet to either of two active positions connecting said inlet to either of said outlets; a rockable member journaled on the boom pivot and connected to one valve part at a point eccentric to said boom pivot; means connecting the other valve part to the support; servo means connected to the bucket eocentrically of the bucket pivot and connected to said rockable member eccentrically of the boom pivot and operative when the boom is raised or lowered to turn the rockable member for incurring an active position of the valve parts so as to operate the bucket motor for leveling the bucket relative to the boom and operative in response to leveling of the bucket to cause the rockable member to return the valve parts to their neutral position; and a manually operated device in the valve part connecting means enabling adjustment of said valve parts to eflect manual operation of the valve means independent of operation of the valve means by the servo means.

2. The invention defined in claim 1, including: a yieldable means acting to center the valve parts in their neutral position and enabling changing of the valve parts to either active position apart from the servo means.

3. In a loader as in claim 1 in which the means for raising and lowering the boom includes a pressure source, a boom lifting and lowering motor, and a boom valve connected to the pressure source and boom motor and having a discharge outlet, the further improvement residing in a fluid conduit connecting the discharge outlet of the boom valve to the pressure inlet of the bucket motor valve.

4. The invention defined in claim 1, in which: said device includes a movable manual member, movable through a range greater than the movement required to change the valve parts from their neutral position to either active position and spring-loaded linkage connected to said member and to said one valve part and enabling the manual member to overrun the valve means so as to load said linkage and thereby to apply a continuing force to the valve means for retaining an active position of the valve parts irrespective of action of the servo means.

5. In a loader having a support mounting the aft end of a fore-and-aft boom on a transverse boom pivot, a bucket carried by the fore end of the boom on a transverse bucket pivot for fore-and-aft tilting to opposite sides of a generally level position and means for eifecting raising and lowering of the boom, the improvement residing in means for correctively maintaining, said level position of the bucket a the boom is raised and lowered, comprising: means including a reversible fluid motor connected between the boom and the bucket for tilting the latter selectively fore-and-aft about the bucket pivot; valve means including a pressure inlet and a pair of motor outlets connected respectively to opposite sides of the motor and a pair of relatively movable valve parts change able from a neutral position cutting off the motor outlets from the pressure inlet to either of two active positions connecting said inlet to either of said outlets; a first sheave journaled on the boom pivot and having an arm fixed thereto and extending therefrom eccentric to the boom pivot; means connecting said arm to one valve part; means connecting the other valve part to the support; a second sheave coaxial with the bucket pivot and fixed to the bucket; a flexible element having one end wrapped about and secured to the second sheave and extending to and wrapped around the first sheave and having a free end and tension spring means connected to said free end and to the boom to maintain tensions in said element whereby said element is operative when the boom is raised or lowered to transmit turning movement of the second sheave to the first sheave for incurring an active position of the valve parts so as to operate the bucket motor for leveling the bucket relative to the boom and operative in response to leveling of the bucket to cause the rockable member to return the valve parts to their neutral position.

6. In a loader as in claim 5 in which the boom is hollow, the further improvement residing in disposition of the flexible element within said hollow boom.

References Cited in the file of this patent UNITED STATES PATENTS at; am... 

